Even though the guide was developed with a hunter, the guide can be followed by any class. Except you have to do your class's quests which aren't a whole lot. I do have full intention to make my guide friendly with all classes in the future by listing all of their steps as well. There will be a toggle that allows you to show which class's steps you want to see in the guide. But this is coming later.
This Shadow Talent Build is the fastest for Leveling Up a Priest Class from 1-60 in WoW Classic patch 1.12. Spamming Shadow Damage DOTs while kite mobs will be the name of the game with this build, having the ability to sustain your health is just a bonus. You will just need to make sure you are stacking enough spirit so you don’t run out of mana often as that will slow down the levelling process drastically.
Monstrous Plaguebats (market GREEN on the map) - These are larger cousins of the normal Plaguebats. They occupy northern parts of the Eastern Plaguelands and drop Vendor Trash Items (Evil Bat Eye, Bat Ear, Sleek Bat Pelt, and Large Bat Fang), Wicked Claws (used in Leatherworking and Blacksmithing Recipes), and maybe some 16 Slot Bags. These can also be skinned for Rugged Leather, Thick Leather, Thick Hide, and Rugged Hide, so Skinning Profession is recommended for Farming them. Monstrous Plague bats have access to the Sonic Burst ability, which is a 10-second Silence, so they are not a good choice for Spellcasting Classes. Recommended Level - 56+.
The Horde 12-20 (Barrens + Stonetalon Mountains) guide has been rewritten and revamped. In addition, there has been numerous tweaks to the speedrun route to make things faster and easier to follow. Also, in case you haven't noticed I am now adding about 40% more info per step and redoing all the images. Unlike with my previous vanilla guides, I am now giving a brief explanation of where to go and what to do with each step along with any other helpful tips.